ACRN/DM: Destroy the created pci_device iterator to fix memory leak in passthru_init

Now it will call the below function to create the corresponding pci_device_iterator
in passthrough device initialization. But it is not released in time.
So it needs to be released to fix the memory leak issue.

Tracked-On: #2762
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Reviewed-by: He, Min <min.he@intel.com>
Acked-by: Yin Fengwei <fengwei.yin@intel.com>

devicemodel/hw/pci/passthrough.c

@@ -815,6 +815,7 @@ passthru_init(struct vmctx *ctx, struct pci_vdev *dev, char *opts)
 			break;
 		}
 	}
+	pci_iterator_destroy(iter);
 
 	if (error < 0) {
 		warnx("No physical PCI device %x:%x.%x!", bus, slot, func);